Mark R,
I see that you are a SoCal fellow. So obviously not a "dense" city boy. In NYC , other dense downtowns and museums all over, people in very crowded spaces ( sometimes mandatorily) wear their day packs on their front. Strange feeling at first, but not hard to accomadate after a bit . Choose you daypack size & fit accordingly. If pickpockets are a concern , those little TSA combo locks can be used on the zip pulls. A more expensive resolution is one of the special anti slash, grab or pickpocket packs. Several brands. Google is your friend.
As to cash, split it up all over your person, wallet ( very little) , off side or rear pocket, sock, shoe, neck wallet, bra, underwear , etc. I also have stopped carrying coins. Pay phones are almost non-existent and existing ones allow use of credit cards. Vending machines & laundamats take bills or plain don't work in a power outage. If you can afford it, $1000 is ideal. 2, $100s; 2, $50s, 30, $20s, balance in $10s, $5s and $1s, split in 3 equal stashes. Work up to it over time. Also a good idea to split up your credit cards, if you have 2 or more.
Same idea is to photo your passport, driver's license, medical insurance ID, health conditions card. Finally, I'm a big believer in wearing a MedicAlert Foundation medallion or bracelet. Instant ID, notice of medical conditions, toll free phone number to supply other medical/ personal info. EMTs know to look for it. No personal connection . But , I am a satisfied subscriber.